1. Field of the Invention
The present invention relates to a combined sedimentation and pressure floatation wastewater treatment tank. More particularly, the present invention relates to a sedimentation arrangement and pressure floatation arrangement incorporated in a single wastewater treatment tank for providing a dual treatment function.
2. Description of the Related Art
In general, wastewater treatment covers several wastewater treatment methods, according to physical properties, for the removal of solid sludge contained in the wastewater. If the sludge is lighter, a pressure floatation method is employed and implemented in a wastewater pressure floatation treatment tank or facilities, for example. If solids and large particles of the sludge are heavier, a sedimentation method is employed and implemented in a wastewater sedimentation treatment tank or facilities, for example. However, both the pressure floatation method and the sedimentation method are well-developed wastewater treatment technologies.
For example, Taiwanese Utility Model Patent No. 324684, entitled “Oil-stock tank for pressure floatation treatment,” discloses an oil-stock structure of a pressure floatation tank, and Taiwanese Utility Model Patent No. 265409, entitled “Improved oil-stock tank structure,” discloses an improved oil-stock tank structure for pressure floatation treatment.
U.S. Pat. No. 5,021,165, entitled “Oil and water separating system with hydrocyclone and floatation device,” discloses a pressure floatation method for oil and water separation treatment. U.S. Pat. No. 4,448,681, entitled “Floatation arrangement,”discloses a pressure floatation arrangement. U.S. patent application publication No. 20080006577, entitled “Method and apparatus for wastewater treatment using nitrogen/phosphorous removal process combined with floatation separation of activated sludge,” discloses a pressure floatation separation method and an apparatus thereof. Each of the above-mentioned Taiwanese and US patent application publications and issued patents is incorporated herein by reference for purposes including, but not limited to, indicating the background of the present invention and illustrating the state of the art.
As a matter of fact, in wastewater treatment processes, there are grease, organic solvents and other equivalent waste materials contained in the wastewater. In some circumstances, changes of wastewater sludge properties will result in enlarging or shrinking sizes of flocs contained in the wastewater. Simply employing either of the pressure floatation method or the sedimentation method cannot achieve the complete removal of the solid sludge contained in the wastewater. Consequently, a great amount of remnant sludge remaining in the waste water treatment tank will overflow into the environment. Hence, the remnant sludge will affect the quality of the treated wastewater when processing a single treatment selected from the pressure floatation method and the sedimentation method.
As has been discussed above, these patents do not disclose a combined device for incorporating different wastewater treatment methods. However, the single treatment of either the pressure floatation method and the sedimentation method cannot achieve the complete removal of the solid sludge contained in the wastewater. Hence, there is a need of improving the conventional pressure floatation method and the conventional sedimentation method for enhancing the efficiency of removing the solid sludge.
As is described in greater detail below, the present invention provides a combined sedimentation and pressure floatation wastewater treatment tank. A sedimentation arrangement and pressure floatation arrangement incorporated in a single wastewater treatment tank provides a dual treatment function in such a way as to mitigate and overcome the above problem.